We propose to study the rheological properties of the vitreous humor of the eye in vitro and to model the motion of the vitreous in order to evaluate methods of optically determining the properties in vivo. The long-term objective is to develop a noninvasive method to diagnose those changes in the vitreous' state in humans which are known to be age-related and which are associated with ocular disorders such as retinal detachment. The research is planned along two lines: (1) In vitro measurement of the rheological properties of the vitreous: The significant parameters are the viscoelastic storage and loss moduli of the vitreous as a function of position and frequency. We will use the magnetic microrheometer, a device developed in our Department for determining the rheological properties of very samll gel samples. (2) An analysis of the quantitative relations between the physicochemical parameters and vitreous motion dynamics will be developed to provide a framework in which to interpret in vivo data. The analysis will allow determination of vitreous flow properties from noninvasive optical measurement of the motion of the vitreous, as a function of spatial gradients, shear dependence, and different boundary conditions specifying the coupling between the vitreous body and the eye.